Optical arrangement with a telecentric beam region

ABSTRACT

An optical arrangement with telecentric beam region for imaging objects, preferably a microscope, comprises in a main beam path at least one infinity-imaging objective and at least one eyepiece with an eyepiece intermediate image plane and a tube lens of suitable focal length which is arranged between the latter at a fixed distance from the objective. At least one optical element in the form of a beam splitter module or beam splitters for laterally splitting off at least a first partial beam path is provided in the space between the objective and the tube lens in which the telecentric beam path is located. A tube lens is located at a suitable distance from the objective in each of these first partial beam paths. At least a second partial beam path is branched off from at least one of these first partial beam paths and a tube lens is located at a suitable distance from the objective in each of these second partial beam paths. The tube lenses arranged in the individual partial beam paths have the same focal length or different focal lengths.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority of International Application No.PCT/EP2003/007316, filed Jul. 8, 2003, and German Application No. 102 35388.3, filed Aug. 2, 2002, the complete disclosures of which are herebyincorporated by reference.

FIELD OF THE INVENTION

The invention is directed to an optical arrangement with a telecentricbeam region with an infinity-imaging objective, in particular amicroscope.

DESCRIPTION OF THE RELATED ART

Optical arrangements, particularly microscopes, with a beam pathencompassing a telecentric beam region have so-called infinity opticswhich comprise infinity-imaging objectives and a tube lens that isarranged at a fixed distance from the objective. This telecentric beamregion is located between the objective and the tube lens. Instead ofone tube lens, a plurality of tube lenses of different focal lengths arealso occasionally accommodated in a revolving turret for purposes ofchanging magnification. To generate a corrected intermediate image atthe distance of the intersection length of the tube lenses, anaberration correction can be carried out exclusively by means of theobjective. However, this correction can also be divided between theobjective and tube lens. In both cases, it is necessary to arrange theindividual optical components at a defined distance from one another andto maintain this distance in order to prevent aberrations andvignetting.

The telecentric beam region situated between the objective and tube lensis conventionally used in microscopes in the direction of the microscopeaxis to introduce optical plane elements, e.g., prisms, splittermirrors, plane plates, filters, polarizing elements, into the imagingbeam path of the device without negatively influencing the intermediateimage. Optics which generate an image offset to compensate for largeroptical paths are not required.

The optical plane elements are usually located in the imaging beam pathin which they are positioned one above the other in different planesperpendicular to the microscope axis, either in a fixed manner or sothat they can be switched into the beam path. Since the telecentric beamregion defined by the distance between the objective and tube lens maynot exceed a determined upper limit for known optical reasons, themaximum quantity of components that can be introduced is limited.Further, the telecentric beam region is also limited toward the side andtoward the back by structural factors of the device, particularly by thedevice body.

DE 42 31 470 A1 discloses a modular microscope system which has amultipart microscope base body having a stand base, an upper stand partand an intermediate module with an attachable binocular housing. Thebase body is a multipart frame construction on which locating surfacesare provided for positioning supports on which are arranged opticaland/or mechanical and/or electric or electronic subassemblies that arecombined to form functional units. Optical components such as mirrors,lenses, diaphragms or a revolving turret unit can be mounted on thesesupports. Further, an intermediate module can be provided which has atube lens and which can be exchanged for another intermediate modulewhich has, for example, a switchable and preadjusted Bertrand lens inaddition to a tube lens.

The above-cited reference discloses an adjustable body of a microscopesystem comprising optical-mechanical modules which are closed, per se,but which do not allow any branch-type expansion of the telecentric beamregion, except for the branching of the illumination beam path which isalways provided.

OBJECT AND SUMMARY OF THE INVENTION

Therefore, it is the primary object of the invention to provide anoptical arrangement with a telecentric beam region that is expanded in aplurality of coordinate directions.

According to the invention, this object is met by an optical arrangementwith telecentric beam region for imaging object comprising at least oneinfinity-imaging objective, at least one eyepiece and a tube lens ofsuitable focal length which is arranged between the two at a fixeddistance from the objective. At least one optical element is providedfor laterally splitting of at least a first partial beam path in thespace between the objective and the tube lens in which a telecentricbeam path is located. A tube lens is located at a suitable distance fromthe objective in each of said first partial beam paths.

At least one optical element for laterally branching off at least afirst partial beam path is provided in the space between the objectiveand the tube lens, that is, in the telecentric beam region in which thetelecentric beam path is located, wherein a tube lens is located at asuitable distance from the objective in each of these first partial beampaths.

In order to expand the telecentric beam region to two coordinates also,it is advantageous when at least a second partial beam path branches offfrom at least one of these first partial beam paths and when a tube lensis located at a suitable distance from the objective in each of thesesecond partial beam paths.

A three-dimensional expansion of the telecentric beam region canadvantageously be realized when at least a third partial beam path isbranched off from at least one of these second partial beam paths andwhen a tube lens is located at a suitable distance from the objective ineach of these third partial beam paths.

It is advantageous that the tube lenses arranged in the first, secondand third partial beam paths have the same focal length or differentfocal lengths. Accordingly, depending upon the requirements for couplingin and coupling out beam paths, the focal length of the provided tubelenses can also be varied. When the focal lengths of all of the tubelenses that are used are the same, there is an identical imaging scalefor all of the intermediate images that are provided.

A further advantage consists in that optical and/or physical beamsplitter elements, known per se, are provided for branching the first,second and third partial beam paths, wherein these beam splitterelements are arranged in the space between the objective and therespective tube lens of the partial beam path to be branched.

For operation and for purposes of multivalent applications of thedevice, it is advantageous to provide interchangeable devices or moduleswhich carry beam splitter elements and which are coupled withcontrollable drive units for the purpose of insertion into therespective partial beam path. This ensures that the beam splitterelements can be exchanged faster and in a more mechanized andcontrollable manner and that they can be moved quickly into therespective beam path. Accordingly, it is also advantageous when the beamsplitter elements are arranged in the interchangeable devices in anexchangeable manner.

For purposes of a versatile use of the device according to theinvention, it is advantageous when diaphragms and/or optical filters,particularly interference filters, color filters or polarizing filters,which serve to influence the optical characteristics of the light of therespective partial beam path are arranged in the first, second and/orthird partial beam paths.

An expansion of the telecentric beam region of optical arrangements,particularly microscopes, can be realized by the invention in a simplemanner in a plurality of coordinate directions while retaining a goodoptical correction of the imaging system. The telecentric beam regionwhich is expanded in this way can accordingly be used for many purposesby coupling in or coupling out intermediate images or other beam paths.In this way, it is possible to expand the telecentric beam region incase of additional application requirements. Another advantage of thearrangement consists in that the ergonomic eyepiece height or viewingheight of the microscope tube is maintained because the length of thetelecentric beam region in the direction of the optical axis of the mainbeam path of the microscope is not changed by the expansion of thetelecentric beam region according to the invention.

The invention will be explained more fully in the following withreference to an embodiment example.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 shows a highly simplified view of an optical arrangement with twopartial beam paths that are branched off in the telecentric beam region;

FIG. 2 shows a perspective view of an arrangement with branched partialbeam paths; and

FIG. 3 shows a highly simplified view of an arrangement with partialbeam paths that are branched off in three dimensions.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a highly simplified view of an optical arrangementaccording to the invention, for example, a microscope beam path, whichis used for magnified imaging of an object 1. The optical arrangementcomprises, along an optical axis 2, an infinity-imaging objective 3, atube lens 4 and an eyepiece 5 with an eyepiece intermediate image plane6 in which the object 1 is imaged by the objective 3 and the tube lens4. The image of the objective 3 generated in the eyepiece intermediateimage plane 6 can be observed through the eyepiece 5 in a magnifiedmanner. The objective 3, tube lens 4 and eyepiece 5 form the typicalmicroscope beam path which forms the main beam path in the opticalarrangement. In the beam path of the arrangement, the infinity-imagingobjective 3 generates a parallel beam path and the image generation inthe eyepiece intermediate image plane 6 is carried out through the tubelens 4 which has a suitable focal length. The telecentric beam region ofthe main beam path is located between the objective 3 and the tube lens4, i.e., the course of the beam is parallel in this region. Thistelecentric beam region, or telecentric space, is usually used in thedirection of the optical axis 2 to arrange optical plane elements suchas prisms, splitter mirrors, and plane-parallel plates as filters and/orpolarizing elements in the beam path without negatively influencing theintermediate image in the eyepiece intermediate image plane 6.

As can also be seen from FIG. 1, optical elements are provided in thetelecentric beam region as beam splitters 7 and 8 for laterallysplitting off (in the X-Y plane) two first partial beam paths in whichtube lenses are arranged. Accordingly, a tube lens 9 is located in thepartial beam path that is branched off by the beam splitter 7. Forexample, a revolving turret 11 which is rotatable on a shaft 10 and hasa plurality of tube lenses 12; 13 of different focal lengths is arrangedin the partial beam path that is branched off by beam splitter 8.Depending upon the purpose for which they are used, these different tubelenses 9; 12; 13 can be moved into the corresponding partial beam pathsthat are branched off from the main beam path. A camera can also bearranged downstream of a tube lens of this kind, for example.

The beam splitters 7 and 8 can be combined to form a beam splittermodule (shown in dashed lines in FIG. 1) which is arranged, e.g., as aunit, in the corresponding beam path. Depending upon the purpose of theapplication, the beam splitter module can be provided with differentdeflecting elements such as color splitters, neutral splitters or fullreflectors. In addition, optical plane elements such as filters ofvarious types can be arranged in the beam splitter module. It is alsopossible for the beam splitter module to be moved in and out of thecorresponding main beam path or partial beam path in a switchablemanner. These switchable beam splitter modules can also be provided withcontrollable drive units (not shown).

The tube lenses 4; 9; 12; 13 define the respective telecentric beamregion of the main beam path and partial beam path in which they arearranged and thus form an optical interface. These tube lenses 4; 9; 12;13 can also be arranged in a mechanical adapter (not shown) which hascorresponding connection surfaces and can accordingly form suitablemechanical interfaces. These adapters can accordingly be arranged atsuitable positions in the individual beam paths. In this way it is alsopossible to use one and the same tube lens and the associated mechanicaladapter, including its interface, for a variety of purposes.

The arrangement, shown in a perspective view in FIG. 2, for magnifiedimaging of small objects 1, for example, a microscope, likewise has amain beam path in which the objective 3, the beam splitter 7; 8, thetube lens 4 and the eyepiece 5 with the eyepiece intermediate imageplane 6 are arranged along the optical axis 2. Since these opticalcomponents in the main beam path have the same functions as thecomponents used in the arrangement according to FIG. 1, the samereference numbers are used. The same applies to the arrangementaccording to FIG. 3 which will be described in the following.

In the optical arrangement according to FIG. 2, another beam splitter 14is arranged in the first partial beam path which is branched off by thebeam splitter 7. Downstream of this beam splitter 14 are arranged, inorder, in another partial beam path another tube lens 15 with a suitablefocal length, and other optical elements, e.g., diaphragms 16; 17,filter 18 and possibly a light source 19 or a display screen. Anotherillumination beam path, for example, can be reflected into the main beampath by the light source 19.

A tube lens 20 and another eyepiece 21 for observing the object 1, e.g.,by a second person, are provided in another, second partial beam pathwhich is branched off from the first partial beam path by beam splitter14.

Another first partial beam path is branched off from the main beam pathby the beam splitter 8 that is situated in the main beam path and isbranched further by another beam splitter 22. Suitable tube lenses 23;24 are again arranged in each of these branched off second partial beampaths; other optical imaging devices, beam-guiding devices and/orviewing devices, not shown, can be arranged downstream of the tubelenses 23; 24. These tube lenses 15; 20; 23; 24, like tube lens 4 in themain beam path, define the telecentric beam region of the partial beampath in which they are arranged. By means of this kind of arrangement ofthe optical elements, an expansion of the telecentric space the X-Yplane can be realized in a simple manner, while maintaining the viewingheight of the eyepiece 5 of the main beam path, for example.

In the description and in the claims, a partial beam path which isbranched off directly from the main beam path is referred to as a“first” partial beam path, and a partial beam path which is branched offfrom a “first” partial beam path is referred to as a “second partialbeam path. A partial beam path which is branched off from a “second”partial beam path is referred to more exactly as a “third” partial beampath.

FIG. 3 shows an optical arrangement in which a telecentric beam regionwhich is expanded in the X-Y plane is also expanded in z-direction foradditional coupling in and coupling out of beam paths, for illumination,or for microtools. The objective 3, the tube lens 4 and the eyepiece 5with the eyepiece intermediate image plane 6 are also arranged along theoptical axis 2 in this arrangement, e.g., a microscope, for magnifiedimaging or observation of the object 1. As in the arrangements accordingto FIGS. 1 and 2, these optical components form the main beam path. Beamsplitter modules 25 and 26 are provided in the main beam path as beamsplitters, shown in a simplified manner as reflectors, for generatingfirst partial beam paths which can be switched in and out of this beampath as is represented by the double arrows in FIG. 3.

It will be seen in FIG. 3 that the beam splitter module 25 forms a firstpartial beam path with another beam splitter module 27 by which secondpartial beam paths are branched off in the X-Y plane by tube lenses 28and 29 in the X-Y plane. A light source 30, for example, for additionalillumination of the object 1 is arranged in one of these second partialbeam paths. The other second partial beam path is split by another beamsplitter 31 into a third partial beam path with a tube lens 29 and intoanother third partial beam path with a tube lens 32. The latter partialbeam path extends in an optical axis parallel to the z-axis resulting ina three-dimensional expansion of the telecentric beam region of thearrangement.

The other first partial beam path generated by the beam splitter module26 is similar in construction to the first partial beam path generatedby the beam splitter module 25. This beam splitter module 26 can also bearranged so as to be swivelable, which is indicated in FIG. 3 by dashes.A beam splitter module 33 that is arranged downstream of the beamsplitter module 26 further branches the first partial beam path that isgenerated by beam splitter module 26. Another beam splitter 34 followsdirectly in one branched second partial beam path and generates thirdpartial beam paths in which suitable tube lenses 35 and 36 are arranged;additional optical components can follow the latter. For example, acomparison plate 38 such as is used in metallography for comparingpolished section samples, etc. and which is illuminated by anillumination device can be made to coincide with an image of the object1 in an intermediate image plane, so that the object 1 can be compared,for example, with a model or standard.

Another third partial beam path which is branched off by the beamsplitter 34 and in which a tube lens 39 is arranged extends in adirection parallel to the z-axis, so that a spatial expansion of thetelecentric beam region is also provided in this case.

In the optical arrangement according to the invention shown in FIG. 3,the individual beam splitter modules and beam splitters can also bearranged in such a way that they can be switched in and out (doublearrow in FIG. 3) of the respective partial beam path in a useful mannerso that additional imaging beam paths, observation beam paths andillumination beam paths can be realized simultaneously and alternately.

The optical arrangement according to the invention permits thetelecentric beam region, spatially defined per se, of a microscope beampath to be expanded in the plane as well as three-dimensionally. In thisway, a quantity of additional beam paths can be mixed in and removedfrom the microscope beam path and the range of application of themicroscope can be expanded.

While the foregoing description and drawings represent the presentinvention, it will be obvious to those skilled in the art that variouschanges may be made therein without departing from the true spirit andscope of the present invention.

REFERENCE NUMBERS

-   1 object-   2 optical axis-   3 objective-   4 tube lens-   5 eyepiece-   6 eyepiece intermediate image plane-   7; 8 beam splitter-   9 tube lens-   10 shaft-   11 revolving turret-   12; 13 tube lens-   14 beam splitter-   15 tubelens-   16; 17 diaphragms-   18 filter-   19 light source-   20 tube lens-   21 eyepiece-   22 beam splitter-   23; 24 tube lens-   25; 26 beam splitter module-   27 beam splitter module-   28; 29 tube lens-   30 light source-   31 beam splitter-   32 tube lens-   33 beam splitter module-   34 beam splitter-   35; 36 tube lens-   37 illumination device-   38 comparison plate-   39 tube lens

1. An optical arrangement with telecentric beam region for imagingobjects, comprising: at least one infinity-imaging objective; at leastone eyepiece; and a tube lens of suitable focal length which is arrangedbetween the two at a fixed distance from the objective, at least oneoptical element for laterally splitting off at least a first partialbeam path being provided in the space between the objective and the tubelens in which a telecentric beam path is located; and a tube lens beinglocated at a suitable distance from the objective in each of said firstpartial beam paths wherein the tube lenses arranged in the first, secondand third partial beam paths have the same focal length or differentfocal lengths.
 2. The arrangement according to claim 1, wherein at leasta second partial beam path is branched off from at least one of thesefirst partial beam paths, and wherein a tube lens is located at asuitable distance from the objective in each of these second partialbeam paths.
 3. The arrangement according to claim 2, wherein at least athird partial beam path is branched off from at least one of thesesecond partial beam paths, and wherein a tube lens is located at asuitable distance from the objective in each of these third partial beampaths.
 4. The arrangement according to claim 1, wherein optical and/orphysical beam splitter elements, are provided for branching the first,second and third partial beam paths, wherein these beam splitterelements are arranged in the space between the objective and therespective tube lens of the partial beam path to be branched.
 5. Thearrangement according to claim 1, wherein interchangeable devices ormodules are provided which carry beam splitter elements and which arecoupled with controllable drive units for the purpose of insertion intothe respective partial beam path.
 6. The arrangement according to claim5, wherein the beam splitter elements are arranged in theinterchangeable devices in an exchangeable manner.
 7. The arrangementaccording to claim 1, wherein diaphragms and/or optical filters,particularly interference filters, color filters or polarizing filters,which serve to influence the optical characteristics of the light of therespective partial beam path are arranged in the first partial beampaths, second partial beam paths and/or third partial beam paths.
 8. Thearrangement according to claim 7, wherein the optical filters areinterference filters, color filters or polarizing filters.
 9. An opticalarrangement with telecentric beam region for imaging objects,comprising: at least one infinity-imaging objective; at least oneeyepiece; and a tube lens of suitable focal length which is arrangedbetween the two at a fixed distance from the objective, at least oneoptical element for laterally splitting off at least a first partialbeam path being provided in the space between the objective and the tubelens in which a telecentric beam path is located; and a tube lens beinglocated at a suitable distance from the objective in each of said firstpartial beam paths wherein the tube lenses arranged in the first, secondand third partial beam paths have the same focal length or differentfocal lengths and interchangeable devices or modules are provided whichcarry beam splitter elements and which are coupled with controllabledrive units for the purpose of insertion into the respective partialbeam path.